I've continued to hack away at it, and it's been coming along, even though I still suck at it. Tonight I foolishly decided to record myself playing it: here's the recording for those of you who enjoy listening to blues piano classics being slaughtered. The ending in particular has great amusement value.
And while I'm at it, here's what happens when I use the power of MIDI to speed things up. Even the mistakes sound better when accelerated to 175 bpm from 115!